json字段示例：

{
"function_id":10,
"function_status":1,
"world_coord_x":30.0,
"world_coord_y":30.0,
"world_coord_angle":30.0,
"head_pitch":30.0,
"head_yaw":30.0,
"timestamp":"1649037880020",
"world_line_info":[1.1,1.1,1.1,2.2,2.2,2.2,3.3,3.3,3.3]
}

解析示例：

#include "json.h"  //必须调用的头文件
Json::Reader reader;  //调用json的reader函数
Json::Value resp;
reader.parse(const std::string& msg, resp);

struct Line_Info{
   float    x1;  
   float    x2;    
   float    x3;     
};

std::vector<Line_Info>  msg_vt_line_info;
struct Line_Info line_info;
if (resp.isMember("world_line_info")) {
   Json::Value parse_line_info = resp["world_line_info"];
   for (int i = 0; i < parse_line_info.size(); i += 3) {
       line_info.x1 = parse_line_info[i].asFloat();
       line_info.x2 = parse_line_info[i+1].asFloat();
       line_info.x3 = parse_line_info[i+2].asFloat();
       msg_vt_line_info.push_back(line_info);
   }
}